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Fuji Electric’s General-purpose
Inverter Aims to be No. 1
Masaru Yamazoe
1. Introduction general-purpose inverter that used a bipolar junction
power transistor (BJT). The development of this
In 1977, Fuji Electric developed and began to sell device was enabled by breakthroughs that increased
the first general-purpose transistor inverter for indus- the voltage and current levels of power transistors and
trial use, thereby paving the way for variable-speed also by advances in the technology for power transistor
drives that use inexpensive standard motors. In the 27 applications. Thereafter, general-purpose inverters
years since then, as the consistent leader in the have continued their development in tandem with the
industry, the Fuji Electric Group has worked to progress in technical innovation.
innovate the technology of general-purpose inverters Figure 1 summarizes the progress of Fuji Electric’s
and has established the general-purpose inverter as an general-purpose inverters. In 1982, Fuji developed the
indispensable equipment for industrial applications. FRENIC5000G and FVR-G series of general-purpose
The progress of the general-purpose inverter can be inverters that utilized sinewave PWM (pulse width
described in terms of advances toward smaller size, modulation) control. Originally, we only provided a
higher performance and lower prices. 200 V power supply series, but after a 1,000 V power
This paper looks back on the progress of Fuji transistor was developed, we commercialized a 400 V
Electric’s general-purpose inverters, describes future power supply series in 1982 as our basic series. This is
technologies to provide the functionality and perfor- said to be the beginning of the history of modern
mance required for future general-purpose inverters, general-purpose inverters. Because a general-purpose
and also discusses future goals of Fuji Electric’s inverter is capable of easily operating a standard
general-purpose inverters. motor at variable speeds, the use of general-purpose
inverters quickly became popular in various industrial
2. Progress of Fuji Electric’s General-purpose applications including woodworking machines, convey-
Inverters ance machinery such as conveyors and dollies, fans
and pumps, food processing machines, and the like.
In 1977, Fuji Electric introduced the world’s first Noticing that general-purpose inverters are highly
Fig.1 Progress of Fuji Electric’s general-purpose inverters
1980 (Year) 1985 1990 1995 2000
S11 (Super compact,
easy operation)
F P P2 P3
C9 (Compact type, no DB)
C11 (Built-in PID FRENIC-
G2 (16-bit
General-purpose inverter
G controller) Mini
microcomputer) G5/P5(All digital control) G7/P7 (LCD display)
FVR B7/G7N Permanent magnet
synchronous motor
K5 (simple K7 (3.7 kW or less)
type)
E7 (Super-low acoustic E9 (Torque E11
noise as a standard feature) vector control)
G2/ G5/P5 (Flux G9/P9 (Torque vector G11/P11 (Dynamic torque
P G P2 G3/P3 control) G7/P7 (Torque calculation) control) vector control)
FRENIC
5000
G6N (Super-low acoustic Permanent magnet
noise) synchronous motor
General
-purpose VG (Vector control) VG3/VG3N VG5 VG7
vector control
inverter
Fuji Electric’s General-purpose Inverter Aims to be No. 1 11
effective in saving energy, especially in variable torque of a general-purpose inverter that utilized this IGBT.
drive applications for fans, pumps and the like, we Fuji Electric introduced the FRENIC5000G6N se-
developed and brought to market the FRENIC5000P ries, which utilized an IGBT, in 1989. By using an
and FVR-P series, one after another. Our product line IGBT, the carrier frequency was increased to 10 kHz or
initially had a capacity up to 70 kVA, but following the greater, thereby eliminating the harsh, unpleasant
development of a 1,200 V, 300 A power transistor, we motor noise and consequently there was an increase in
increased the capacity of our product line to enable the general-purpose inverter usage at locations where
driving of up to a 280 kW motor. In 1986, we brought people were nearby. Thereafter, IGBTs have contin-
to market the FRENIC5000G5 and FVR-G5 series, one ued to be used as the power devices for general-
after another. The FRENIC5000G5 series uses flux purpose inverters. The increase in carrier frequency,
control-type PWM control to reduce the torque ripple of however, created a new problem of electromagnetic
a motor. The FVR-G5 series is not only suitable for noise, which was higher than when BJTs were used,
performing motor control, but it is series of fully digital and this noise affected peripheral devices. Measures to
control inverters that feature digital operation and reduce electromagnetic noise became a serious problem
settings, and was the first inverter series to utilize a 7- for general-purpose inverters. Moreover, power device
segment LED (light emitting diode) display and a key loss was also greater than when BJTs were used, and
pad panel equipped with key switches. The FVR-G5 the measures to reduce this loss are linked to advances
enables necessary parameters for the inverter to be in cooling technology such as the development of heat
displayed and set as digital values, which lead to a sinks and the like.
dramatic increase in multi-functionality and ease of Figure 2 shows the trend of loss generated by
operation. general-purpose inverters. The majority of loss gener-
Introduced to the market in 1994, the FRENIC ated by a general-purpose inverter is the loss attribut-
5000G9 series was the first general-purpose inverter to ed to the power device, and there was a dramatic
incorporate the concept of vector control, and this increase in loss when BJTs were replaced by IGBTs.
series realized a dramatic improvement in perfor- Advances in IGBT technology enabled the next genera-
mance. Thereafter, we introduced the industry’s tion of IGBTs to achieve approximately the same level
smallest inverter, the FVR-C9 series, which was the of loss as BJTs. Moreover, in the G11 series, which
leading product in the industry. Then in 1998, we used the 4th generation of IGBTs, magnetic noise was
introduced the present FRENIC5000G11 series, whose reduced but, as a consequence, loss increased to a level
performance surpassed that of the initial vector con- greater than that of the G9 series which used 3rd
trolled inverters. In 2002, we brought to market the generation IGBTs. Our next generation inverter
most recent and extremely cost effective series, the series, which will use 5th generation IGBTs, is de-
FRENIC-Mini. signed to provide dramatic improvement by reducing
both magnetic noise and loss.
3. Progress of General-purpose Inverter Tech- In order to reduce the size and cost of small-
nology
The progress of inverter technology is the same as Fig.2 Loss in general-purpose inverters
the progress of power electronics technology. Inverter
technology can roughly be classified into the categories 140
IGBT (2nd gen.)
of main circuit technology, control circuit technology,
and motor control technology. 120
IGBT (4th gen.)
3.1 Main circuit technology 100 IGBT (3rd gen.)
Main circuit technology has progressed along with BJT
advances in power devices. By applying PWM control 80 IGBT (5th gen.)
to a full bridge-type inverter that uses a BJT, a
(%)
compact and low-cost general-purpose inverter was
60
realized. When a BJT was utilized, however, the
carrier frequency, which was the switching frequency
of the power device, was several kHz and the motor 40
noise generated by switching at this frequency was
audible as a harsh and unpleasant sound. Moreover, 20
the current ripple was large, and from the present day
perspective, this resulted in large loss by the motor. 0
G7 G7N G9 G11 GX
The problems were resolved by the development of an (Next generation)
IGBT (insulated gate bipolar transistor) that enabled Generation of series
high-speed switching and in 1988, by the introduction
12 Vol. 50 No. 1 FUJI ELECTRIC REVIEW
capacity inverters, Fuji Electric has independently winding machines, extruders and the like that require
developed a power module specifically for inverters. highly responsive and highly accurate speed control
By integrating the inverter’s main circuit terminal performance. Based on this, vector control began to be
with the power module, the circuitry has been simpli- applied to general-purpose inverters in 1990, enabling
fied and made smaller with lower cost. Fuji’s power the high performance control of standard motors.
module for inverters uses our proprietary compound With the advances in control technology, applica-
metal printed circuit board to simplify the cooling of tions for general-purpose inverters have increased.
the miniaturized power module. Figure 4 shows the markets in which drive equipment
are utilized. Recently, general-purpose inverters have
3.2 Control circuit technology also been used in gear-equipped elevators and cranes.
Control circuit technology underwent its largest
change during the transition from analog to digital 4. Future Requirements for General-purpose
circuitry. In particular, in 1986, Fuji Electric was the Inverters
first in the industry to apply fully digital control using
a 16-bit CPU (central processing unit) to create the In looking back at the progress of inverters,
prototype for the modern general-purpose inverter. progress has been made in response to requirements
The higher performance and multi-functionality of for smaller size, higher performance and multi-func-
general-purpose inverters could not have been realized tionality. The expected future requirements of gener-
without advances in CPU technology. al-purpose inverters are listed below.
Figure 3 shows the history of improvement in the (1) Miniaturization has achieved an inverter size that
performance of CPUs used in general-purpose invert- is approximately 1/10 that of an original-stage
ers. Performance improvements have resulted in equivalently functional inverter. Figure 5 shows
approximately 10 times the computational processing the volumetric changes in size of general-purpose
speed and 30 times the program capacity, thereby inverters. Demands for miniaturization are not as
making it possible to realize inverters having higher strong as in the past, but in the future, miniatur-
levels of performance and multi-functionality. More- ization will be requested for general-purpose in-
over, control circuit technology is characterized by an verter systems that include peripheral devices.
appropriate balance between the hardware using LSI (2) Performance and multi-functionality have in-
(large scale integrated circuit) and the software. creased with each successive generation of invert-
er, and with the increase in general-purpose
3.3 Motor control technology inverter applications, there are strong demands
Motor control technology is based on the V/ f for higher performance and greater multi-func-
control of induction motors and enables standard tionality. The increase in multi-functionality of
motors to be operated at variable speeds. The general-purpose inverters has been amazing, but
FRENIC5000VG series, introduced in 1986 as the it can also be said that the utilization of this
industry’s highest precision inverter, uses vector con- multi-functionality has become complicated for the
trol to realize performance comparable to that of a DC end user. Because it is sufficient to provide just
motor, and enables the use of inverters in new the required functions for a particular application,
applications such as cranes, car parking facilities, demand will likely increase for inverters that
allow functions to be selected according to the
application and for user-programmable inverters.
Fig.3 History of CPU performance improvements (3) The market for general-purpose inverters origi-
nated in Japan, but now this market has spread
350 worldwide and is reportedly valued at approxi-
mately 3 billion dollars. Requirements vary
300 somewhat according to country and region, and
Min. execution time of
instruction (ns) the problem of supporting these differences is a
250
challenge for the future. Such considerations
(k bytes), (ns)
200 include, for example, protective structures, termi-
nal structures, anti-noise filters, as well as consid-
150 erations for an open field bus. Moreover, there
has been an increase in various regulations, and
100
compliance with Europe’s CE marking and RoHS
ROM capacity (k bytes)
50 (restriction on hazardous substances) regulations
or the equivalent are being required throughout
0 the world. These various regulations are indica-
G2 G5 G7 G9 G11
Generation of series tions of the heightening environmental concern.
Even in Japan, users are increasingly calling for
Fuji Electric’s General-purpose Inverter Aims to be No. 1 13
Fig.4 Example applications for general-purpose inverters
(large)
Conveyance machines
Packaging machines
Compressors
Home pumps
Pumps (for apartment buildings)
Machine tools
Fan control (for GHP) Sanding machines Cotton textile machines
Printing presses Injection molding
Market machines
size Elevators (with gears) (with gears)
Drawing machines (dancer)
Chemical textile
Husking and drying machines Vacuum pumps machines Drawing machines (straight)
Car parking facilities,
Centrifuges automated warehouses
Hack sawing machines
Ventilating fans
(for livestock barns) Woodworking machines Commercial-use
washers Cranes Elevators (without gears)
High speed motor drive systems
(small)
(slow) Response (fast)
“green procurement” and this will likely be an Fig.5 Changes in size of general-purpose inverters (750 W)
important factor for future inverters.
16,000
14,170
5. Outlook for Future Technology 14,000
Volumetric size (cm3)
12,000
5.1 Main circuit technology
10,000
IGBTs will likely continue to be used for some time
8,000 7,130
as the basic power devices for inverters. The main
6,000
circuits most commonly employ a full bridge inverter
4,000 3,130
using PWM control. Some inverters are trending 1,870
2,000 1,150
toward commercialization as 3-level inverters, but
0
since the cost is high, applications for these inverters FVR-G FVR-G5 FVR-K7 FVR-E9 FVR-C11
will be limited. A reverse-blocking IGBT has been Generation of series
developed and circuits are being designed to best
utilize its features, but applications will likely be
limited due to the high cost. sary to adjust the characteristics of the drive motor,
The most important trend of main circuit technolo- and automatic tuning technology and robust control
gy is toward noiseless circuitry. The increase in technology are expected to evolve as control methods.
magnetic noise caused by switching at a high carrier A shift in control methods, from inductive motor
frequency has been described above, but in a broad driving to synchronous motor driving has been ob-
sense, the development of technology to solve the served. In particular, synchronous motor driving has
problem of noise (magnetic noise, harmonic current already begun to be used in pump applications that
emissions, leakage current, etc.) is crucial and Fuji aim to achieve energy savings, higher speed and
Electric is advancing technical development to realize smaller size. This trend is expected to continue.
a completely noiseless inverter.
5.4 Maintenance
5.2 Control circuit technology General-purpose inverters use components such as
The use of highly integrated LSI chips containing a electrolytic capacitors and cooling fans that have a
CPU core is expected to increase in response to finite lifespan, and therefore, maintenance is essential.
demands for miniaturization and for the application of Efforts are underway to extend the useful lifespan of
high-speed CPUs in order to achieve higher perfor- these components and to develop technology that does
mance and increased multi-functionality. Requests for not use these finite-lifespan components and ultimate-
connection to an open field bus have also resulted in ly general-purpose inverters will not require any
the emergence of inverters containing built-in interface maintenance. For the time being, however, functions
functions as a standard feature. for displaying lifespan information and for outputting
lifespan prediction signals will likely be improved to
5.3 Control method simplify maintenance and to increase reliability.
As performance levels increase, it becomes neces- In addition, internet-based servicing can be used to
14 Vol. 50 No. 1 FUJI ELECTRIC REVIEW
perform maintenance in the case of a malfunction or distributed control systems in which the information of
the like. The ease of use is expected to increase. adjacent inverters is captured and an inverter operates
by evaluating and controlling its own actions. Fuji
6. Future Aims of Fuji Electric’s General-pur- Electric’s general-purpose inverters aim to be able to
pose Inverters support these types of requests too.
Required specifications are diverse and depend on
Fuji Electric first began selling its FRENIC5000G the particular application. The operation and specifi-
series 27 years ago, and has continued to provide cations of a general-purpose inverter are determined
cutting-edge general-purpose inverters that utilize the by a user’s selection of parameters with the integrated
most advanced technology of the time. Based on the function group. In order to support diversification, one
requirements for general-purpose inverters and the solution is to provide the user with programmable
outlook for future technical innovation, future aims of functions. In other words, one realization of this
Fuji Electric’s general-purpose inverters are described concept is a general-purpose inverter provided with a
below. built-in programmable controller (PLC) function.
(1) Wide range of model types (4) Pursuit of cost effectiveness
As the leading manufacturer of general-purpose The trends for general-purpose inverters are di-
inverters, Fuji Electric aims to have a complete line of verging toward the extremes of either single function,
products, from low-end inverters to high-end inverters, low cost products or high-performance, multi-function
and to continue to provide the best-suited inverter for products. However, from the perspective of an applica-
each particular application. Also, in view of the global tion, there is no need for performance and functions in
market, Fuji Electric intends to create a line of excess of what is appropriate for that application. In
different models that range from small to large other words, users are requesting that cost effective
capacity and that support different voltages as in the inverters be provided. For this reason, it is important
case of overseas manufacturers. that there be a standard inverter, which is situated
(2) Environmentally-friendly inverters between the two extremes. Such an inverter is
Fuji Electric aims to make its general-purpose required to be capable of easily supporting user
inverters become noise-free. Although previously requested specifications, and Fuji Electric intends to
considered a source of noise, the development of develop such a standard general-purpose inverter.
inverters that do not adversely affect the peripheral Moreover, the vector inverter that previously used a
devices is an important issue. special motor has recently become able to use a
As represented by the concept of “green procure- standard motor, and the boundary between general-
ment,” there is demand for products manufactured purpose inverters and vector inverters is becoming
without certain hazardous substances. Lead-free prod- blurred. Fuji Electric intends to remove this boundary
ucts have already begun to be used in household and provide users with lower cost and higher perfor-
electrical appliances, and there are similar demands mance inverters.
for making industrial-use general-purpose inverters
lead-free as well. Fuji Electric is already endeavoring 7. Conclusion
to develop general-purpose inverters that do not con-
tain certain hazardous substances, and expects to be This paper has looked back on the advances of Fuji
compliant by 2005 with its newly developed products. Electric’s general-purpose inverters, and discussed the
The FRENIC-Mini, introduced to the market in 2002, future requirements for general-purpose inverters and
is already using lead-free solder in some parts of its Fuji’s aims for its general-purpose inverters.
construction. Fuji Electric intends to continue to promote the
As described above, Fuji Electric’s general-purpose evolution of general-purpose inverters and to provide
inverters aim to become “environmentally-friendly in- the latest general-purpose inverters to the worldwide
verters.” market. Constant technology development and prod-
(3) Support of diverse applications uct development are essential for this purpose. Fuji
In the past, general-purpose inverters were con- Electric is committed to developing new general-
trolled by a concentrated control system whereby purpose inverters by adding new technology to its base
commands were received from a host controller or the of cultivated technology, and to respond to user needs.
like. On the other hand, there are also requests for
Fuji Electric’s General-purpose Inverter Aims to be No. 1 15
